Rotating electric machine and method of manufacturing core

Abstract

To reduce a loss of a rotating electric machine by making it difficult for an eddy current to occur in a welding portion of the rotating electric machine. A rotating electric machine includes a rotor including a magnet on an outer circumferential portion, a stator core having plural teeth facing the outer circumferential portion of the rotor via a gap, an electric insulator covering a part of a surface of the stator core, and plural coils wound around the stator core via the electric insulator. The stator core has plural steel plates stacked in an axial direction. At least two plural steel plates [adjacent to each other in the axial direction, of the plural steel plates, are welded at a position on the surface of the stator core, the position being outside a closed magnetic circuit generated in the stator core. The plural steel plates are not welded at a position on the surface of the stator core where each tooth faces the rotor.

1 . A rotating electric machine comprising:
 a rotor rotatable about an axis line extending in a first direction, the rotor including a magnet at an outer circumferential portion;   a core including plural teeth facing the outer circumferential portion of the rotor via a gap;   an insulator covering a part of a surface of the core; and   plural coils wound around the core via the insulator, wherein   the core includes plural steel plates stacked in the first direction,   each of the plural steel plates has a thickness of 0.3 mm or less in the first direction,   at least two steel plates adjacent to each other in the first direction, of the plural steel plates, are welded at a position on the surface of the core, the position being outside a closed magnetic circuit generated in the core, and   the plural steel plates are not welded at an outer surface of each of the teeth, the outer surface facing the rotor.   
     
     
         2 . The rotating electric machine according to  claim 1 , wherein
 the core includes plural steel plate units each including m pieces of the steel plates stacked in the first direction and bonded to each other with an adhesive, m being an integer of two or more,   each of the steel plate units is stacked in the first direction, and   the steel plates that are located at an end in the first direction in each of the steel plate units and are adjacent to each other in the first direction are welded.   
     
     
         3 . The rotating electric machine according to  claim 1 , further comprising:
 a resin mold surrounding a portion of each of the teeth, the portion being close to the gap.   
     
     
         4 . A rotating electric machine comprising:
 a rotor rotatable about an axis line extending in a first direction, the rotor including a magnet at an outer circumferential portion;   three or more split cores each including:
 a yoke separated from the outer circumferential portion of the rotor in a second direction intersecting the axis line; and 
 two teeth extending from two ends of the yoke in a third direction intersecting the first direction and the second direction, the two teeth facing the outer circumferential portion of the rotor via a gap; 
   three or more insulators covering each of the yokes; and   three or more coils each wound around the yoke via each of the insulators, wherein   each of the split cores includes plural steel plates stacked in the first direction,   each of the plural steel plates has a thickness of 0.3 mm or less in the first direction,   at least two steel plates adjacent to each other in the first direction, of the plural steel plates, are welded at a welding portion outside a closed magnetic circuit generated in the split core on a surface of the split core, the welding portion being at an end of the yoke in the third direction, and   the plural steel plates are not welded at an outer surface of each of the teeth, the outer surface facing the rotor.   
     
     
         5 . The rotating electric machine according to  claim 4 , wherein
 each of the split cores includes three or more steel plate units each including m pieces of the steel plates stacked in the first direction and bonded to each other with an adhesive, m being an integer of two or more,   the three or more steel plate units are stacked in the first direction,   the steel plates that are located at an end in the first direction in each of the steel plate units and are adjacent to each other in the first direction are welded at the welding portion, and   one and another one of two welding portions adjacent to each other in the first direction are at one end and another end of the yoke in the third direction.   
     
     
         6 . The rotating electric machine according to  claim 4 , wherein
 each of the teeth has a surface extending along the second direction from two ends of the yoke in the third direction to the gap.   
     
     
         7 . The rotating electric machine according to  claim 4 , further comprising:
 a resin mold surrounding each of the teeth in an extending end side of each of the teeth.   
     
     
         8 . A rotating electric machine comprising:
 a rotor rotatable about an axis line extending in a first direction, the rotor including a magnet at an outer circumferential portion;   three or more split cores each including:
 a yoke separated from the outer circumferential portion of the rotor in a second direction intersecting the axis line; and 
 two teeth extending from two ends of the yoke in a third direction intersecting the first direction and the second direction, the two teeth facing the outer circumferential portion of the rotor via a gap; 
   three or more insulators covering each of the yokes; and   three or more coils each wound around the yoke via each of the insulators, wherein   each one split core of said three or more split cores includes plural steel plates stacked in the first direction,   at least two steel plates adjacent to each other in the first direction, of the plural steel plates, are welded at a welding portion outside a closed magnetic circuit generated in said one split core on a surface of said one split core, the welding portion being at an end of the yoke in the third direction,   the plural steel plates are not welded at an outer surface of each of the teeth, the outer surface facing the rotor, and   each of the teeth has a surface extending along the second direction from the two ends of the yoke in the third direction to the gap.   
     
     
         9 . The rotating electric machine according to  claim 8 , wherein
 each of the split cores includes three or more steel plate units each including m pieces of the steel plates stacked in the first direction and bonded to each other with an adhesive, m being an integer of two or more,   the three or more steel plate units are stacked in the first direction,   the steel plates that are located at an end in the first direction in each of the steel plate units and are adjacent to each other in the first direction are welded at the welding portion, and   one and another one of two welding portions adjacent to each other in the first direction are at one end and another end of the yoke in the third direction.   
     
     
         10 . The rotating electric machine according to  claim 8 , further comprising:
 a resin mold surrounding each of the teeth in an extending end side of each of the teeth.   
     
     
         11 . A method of manufacturing a core, the method comprising:
 a welding step of stacking plural steel plates in a first direction and welding the plural steel plates, the plural steel plates each having a planar shape of the core and a thickness of 0.3 mm or less, wherein   a welded body produced in the welding step includes a yoke and a tooth extending from the yoke in a second direction intersecting the first direction, and   in the welding step, at least two steel plates adjacent to each other in the first direction, of the plural steel plates, are welded by a welding device at a position outside a closed magnetic circuit generated in the yoke on a surface of the yoke, and are not welded at the tooth,   the manufacturing method further comprises:   covering a surface of the welded body with an insulator; and   winding a metal wire around the insulator.   
     
     
         12 . A method of manufacturing a core, the method comprising:
 a stacking step of bonding plural steel plates with an adhesive and stacking the plural steel plates;   a molding step of forming a steel plate unit by punching the plural stacked steel plates into a shape of the core; and   a welding step of forming the core by stacking the plural steel plate units in a first direction and welding the plural steel plate units to each other, wherein   the core includes:
 a yoke extending in a third direction intersecting the first direction; and 
 two teeth extending from two ends of the yoke in a second direction intersecting the first direction and the third direction, 
   each of the teeth has a surface extending along the second direction from the two ends of the yoke in the third direction,   in the welding step, at least two steel plates adjacent to each other in the first direction, of the plural steel plates, are welded at a welding portion outside a closed magnetic circuit generated in the core on a surface of the core, the welding portion being at the two ends of the yoke in the third direction, and   the plural steel plates are not welded at an outer surface of each of the teeth, the outer surface facing a rotor.   
     
     
         13 . A method of manufacturing a core, the method comprising:
 a welding step of stacking plural steel plates in a first direction and welding the plural steel plates, the plural steel plates each having a planar shape of the core, wherein   a welded body produced in the welding step includes a yoke and a tooth extending from the yoke in a second direction intersecting the first direction, and   in the welding step, at least two steel plates adjacent to each other in the first direction, of the plural steel plates, are welded at a position outside a closed magnetic circuit generated in the yoke on a surface of the yoke, and are not welded at the tooth,   the manufacturing method further comprises:   covering a surface of the welded body with an insulator; and   winding a metal wire around the insulator in a state where a jig is attached to a portion of the tooth that is close to a tooth tip surface and a portion of the tooth that is close to the tooth tip surface is fixed in the first direction.